It is reported that hcatecins act as an inhibitor against a rise in cholesterol level (Japanese Patent Application Laid-Open (kokai) No. Sho 60-156614) or as an α-amylase activity inhibitor (Japanese Patent Application Laid-Open (kokai) No. Hei 3-133928). This suggests that tea beverages such as green tea, black tea and Oolong tea have useful physiological benefits. When these beverages were put on the market, some measures have been taken to improve their taste and color tone or to make them respond to changes upon storage. For example, a method for preparing a beverage by controlling pH upon extraction and preserving the good condition of natural catechins during storing in order to give a desirable state and adjusting the taste and color tone (Japanese Patent Application Laid-Open (kokai) No. Hei 5-168407), a method for sterilizing a beverage under pressure at low temperatures in order to preserve its qualities such as taste for a long period of time (Japanese Patent Application Laid-open (kokai) No. Hei 5-4940177 a method for adding cyclodextrins, thereby alleviating bitterness or astringency particular to catechins (Japanese Patent Application Laid-Open (kokai) No. Hei 10-4919) and a method for removing a retort odor from a green tea beverage (U.S. Pat. No. 2,566,801) are proposed.
The physiological action of catechins can be shown effectively by increasing their intake amount. From the viewpoint of palatability and marketability, beverage forms which facilitate the intake of a large amount of catechins are desirable.
Two methods for increasing the amount of catechins contained as an effective ingredient in a beverage have been reported. One is a method for adding powdered tea leaves (Japanese Patent Application Laid-Open (kokai) No. Hei 10-234301). When catechins are extracted from tea leaves in order to increase the concentration of catechins in a beverage, the resulting beverage becomes inappropriate as a product to be put on the market, because when it is packaged and stored for a long period of time, a marked change in color occurs. The coloration of the beverage gradually changes over time, from a desirable light green color to an ugly brown color. Therefore, there is no problem with such a packaged beverage which contains powdered tea leaves as an effective ingredient when it is consumed directly after production, but it does however lose its product value during a distribution process because of a deteriorated appearance. For example, powdered tea leaves precipitate on the bottom of the container or float on the surface of the beverage. This tendency becomes more marked when a transparent container such as a PET bottle is used. Since opaque containers such as cans cannot be recapped (re-sealed), all the beverage contained therein must be consumed once it is opened. Such a limitation on drinking habits is an inconvenience for customers. Using an opaque PET bottle to hide precipitation does on the other hand, cause a serious problem for recycling. Formation of a precipitate or sedimentation of powdered tea leaves means that the ratio of the ingredients differs between the initial stage of drinking and the latter stage of drinking. However, the addition of a thickening agent to prevent such a phenomenon distorts the smooth feeling in the throat and refreshing taste of the beverage. This is problematic for a beverage providing physiological effects.
The other method for increasing the amount of catechins as an effective ingredient is to add them in dissolved form. When the amount of catechins as an effective ingredient is increased by extraction of tea leaves, the packaged beverage tends to become turbid and a product with such an appearance is not accepted in the market. This turbidity leads to opacity over time and then large visible particles appear in the container.
A beverage having such a color change or turbidity is not visually attractive, which presents a serious problem to be solved when it is put on the market.
The coloration is said to be caused by polyphenol oxide formed by oxidation of catechins.
The turbidity is said to be a phenomenon caused by mutual action between the ingredients of the beverage and the catechins or polyphenol oxide formed by oxidation of catechins. Such a phenomenon tends to occur in acidic or neutral beverages. Turbidity of the beverage becomes prominent when the catechin concentration is increased. The turbidity of the beverage has a negative impact on its appearance and this presents a serious problem to be solved when it is put on the market.
It is presumed that the function of PPAR is to extensively take part in energy metabolism in living bodies and the maintenance of homeostasis, for example, synthesis, transport and secretion of fatty acids, synthesis of ATP in fat-consuming organs and cell-cycle regulation. In particular, it has been revealed that gene expression of β-oxidation related enzymes important for fatty acid metabolism depends greatly on the activation of PPAR.
An object of the present invention is to provide a packaged beverage ving a stable color tone and transparent appearance after long-term storage even with a high catechin content.